With the development of genetic research and allied medical and biological instrumentation including applications such as liquid chromatography, there has developed a need for a means to dispense and control fluids in a manner which exceeds the precision capabilities of existing solenoid valves. This need stems from the requirement to control the flow of fluids in a complex manner and the need to control and dispense fluids such as genetic substances which can be manufactured only in extremely small quantities and at extremely high cost. Along with these critical requirements there is a need to provide a control valve which is not subject to contamination by the fluid being processed.
The increased application of computer technology to the control of fluid processes coupled with the above requirements for precision in the control of fluids leads to a requirement in which not only must the control valve be able to be controlled by a computer, but the state of the valve must be able to be sensed by the computer in a precise manner without errors due to mechanical losses, inertia or mechanical hysteresis.
The need for precision in the delivery of the fluids being processed results in requirements for precision in the construction of valves which exceed the capability of conventional control valves and also exceed the ability to construct a precision valve using known construction methods.